INTERACTION BETWEEN A DRIFTING SPIRAL AND DEFECTS

Spiral waves, a type of ''reentrant excitation,'' are believed to be a ssociated with the most dangerous cardiac arrhythmias, including ventr icular tachycardia and fibrillation. Recent experimental findings have implicated defective regions as a means of trapping spirals which wou ld otherwise drift and (eventually) disappear. Here, we model the myoc ardium as a simple excitable medium and study via simulation the inter action between a drifting spiral and one or more such defects. We inte rpret our results in terms of a criterion for the transition between t rapped and untrapped drifting spirals.